cross post: NEX vs EPL1
This question has been answered multiple times in this forum. You can do a search and get all the detailed answers.
Nex3 is better suited for your Pentax lenses. Better IQ and focus peeking.
EPL-1 with AF lenses like 20 1.7 or 14 2.5 will be better than Nex3 with 16 2.8 .
Dynamic range is a compromise but IBIS in EPL-1will compensate for the ISO if you are shooting static objects.
14 2.5 is better rated than 16 2.8. 16 2.8 is the lowest rated lens for Nex.